Fire and burglar alarm system



(N 0 Model.)

.W. A. BARNES.

. FIRE AND BURGLAR ALARM SYSTEM. r No..380,2 41. Patented Mar. 27, 1888,

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ATTORNEY MPETERS, Phowlflhograplm. Wallinglml, p c.

PATENT OFFICE.

WILLIAM A. BARNES, OF BRIDGEPORT, CONNECTICUT.

FIRE AND BURGLARALARM SYSTEM.

SPECIFICATION forming part of Letters Patent No. 80,241, dated March 2'7. 1

Application filed September 26, 1887. Serial No. 950,645. (No model.)

To ail whom it may concern:

Be it known that 1, WILLIAM A. BARNES, of Bridgeport, Fairfield county, Connecticut, have invented a new and useful Improvement in Fire and Burglar Alarm Systems, of which the following is a specification.

My invention relates to a system for the pro tection of buildings, 8m. from fire or burglars, whereby a signal is given when a conductor led through suitable localities in said building is divided, or when the strength of the current traversing the same is varied.

My invention consists more particularly in the arrangement of apparatus, substantially as hereinafter described and claimed.

The accompanying drawings are electrical diagrams illustrating my hereinafter de scribed system. Figure 1 shows the system as disposed before an alarm is transmitted. Fig. 2 represents the position of armature with reference to adjacent contact-points during the time that an alarm is being sent or afterward.

Similar letters of reference indicate like parts. A

The principle upon which this system depends is that of the electrical equilibrium of two currents in different circuits, or, in other words, an electrical current traversing one conductor is made to exert its energy in opposition to that of another current traversing another conductor. When the opposing energies are made equal, equilibrium results. If, however, from any outside cause the current upon one conductor is made of greater or less strength than the opposing current, then equilibrium no longer exists, and the overplus energy of the greater current is thus rendered free to manifest itself by signals due to its ac tion upon suitable mechanism.

. To cause a current traversing one conductor to balance a current'traversing another conduetor is an elementary electrical problem easilysolved by any one skilled in the art in numerous known ways. A simple method is to wind the two conductors in opposite directions .upon the same iron core. Either conductor as a single coil would on the passage of a current through it render the core magnetic and ofa certain polarity; but the opposite winding of the coils results in magnetic neutrality, inasmuch as the two coils tend toinducepoles of opposite name at the same extremity of said core.

Consequently, if the strength of the currentin the two coils be equal and the thickness of the.

conductor, number of its turns, 8170., the same, the core will not attract an armature so long as this equilibrium continues; but as soon as said equilibrium is disturbedas, for example,

by severing one conductor-the core will attract its armature, which in turn may set in motion alarm mechanism or other signal device.

In the accompanying diagrams, A is an 7 electro-magnet. One coil, B, of this. magnet is included in the branch line C. The other coil,

D, of said magnet is wound in the opposite direction to that of coil B, and is included in the I branch lineE. The two branch lines C and E are disposed in multiple arc. The main line forms a third branch, F F F, or the branch lines 0 D may be regarded as in shunt from the main line F F F.

G is the armature of the electro-magnet A.

An electrical current proceeding from the battery H will divide through the branch lines 0 and E. In passing through the coils B and D of the electro-magnet A the energy of the current in one branch line will be opposed by the energy of the current in the other branch line, and hence no apparent magnetism will be induced in the core of electro-magnet A, and the armature G will remain quiescent; but if, for example,. the branch conduetor C be cut or its continuity be interrupted in any way at any point, then no current' will traverse that conductor nor its coil B, and hence the magnetizing energy of the current in coil D will be unopposed, the core of electro-magnet A will become magnetic,

and the'armature G willbe attracted. The same result will follow ,no matter how the equilibrium between the currents in thebranch lines be disturbed. Thus, assuming the energy of the currents in the two lines to be equal, any change in the resistance of either line will result in a disturbance of magnetic equilibrium. If, to illustrate, a loop conduetor, as indicated by dotted lines, as I, Fig.

1,were connected to the line C, then the -resistance of said line would be diminished, and hence the strength of thecurrent in coil B would to a corresponding extent become greater than the strength of the currentin coil D; or suppose that the resistance at any point of either branch line became augmented from any cause, then the current in the coil included in that line would become weakened, and again the balance would be destroyed and the magnet A would be energized.

In the present diagram I have shown but two branch lines, 0 E, the currents of which are balanced. I may, however, multiply the number of branch lines at will, balancing, for example, two coils wound in one direction against two coils wound in the opposite direc tion, or two coils against one coil, and so on through a great variety of changes,all of which will readily suggest themselves to the skilled electrical workman. In practice the size of the conductors, number of turns, 8m, would be proportioned once for all, and equilibrium eflected by a simple adjustment of relative resistances interposed in the branch circuits. One of the main advantages of this system is the great difliculty which it offers to any one attempting to tamper with it. The branch line C may go to one house, for example, and the branch lineE to another, the magnet Abeing located at any convenient point, any rupture of either branch line C or E or any change in the resistance being certain to affect the magnet A to cause it to move its armature G. Hence, even if a burglar'should know the exact lead of all the circuit-wires, that fact would be of no value to him, for there is apparently nothing which he could do upon one line which would render both branch lines inoperative at the same moment. So, also, where numerous branch lines are provided several pairs of lines balanced against one another may exist. A branch line may run through a certain apartment in a tenement and itsopposingline may be conducted through a far distant apartment, the occupant of neither premises having knowledge as to the locality of the line which balances his own.

Another important advantage of my system, which will appear from the following description of the illustrative mechanism indicated in the diagram, liesin the fact that a constant current is always traversing the system. When a signal is to be sent, this current may be diverted through an automatic signaling mechanism, as hereinafter described.

The system does not depend for its main operation upon the establishment of a current over a protecting-line on which there is no current, and upon which in case of injury or accident the normal condition of no current will continue, but upon acontinuous existing current which cannot be altered or in any wise modified without an alarm resulting.

Referring, now, more particularly to the diagrams,on the armature G is a contact-arm, J, which, when said armature is in the position shown in Fig. 1, (that is, not attracted by the electro-magnet A,) touches a contact-point, M, communicating with line F. The current on the line may therefore pass from point M to arm J, and so to the branch lines 0 E- and magnet-coils D l3, and thence to a contactpoint, N. Armature G is pivoted at 0. Be-

tween the maln body of the armature and the pivot-point is inserted a body of insulating electrical communication along the armature from one end to the other is thus prevented. With an arm, Q, on the other side of the 'armaturepivot O the point N makes contact. Near the extremityof the arm Q, and to any convenient support, 1s pivoted a latch, R, which may be providedwith a coiled spring at S. At T is an ordinary clock-train driven by a coiled spring and rotating the metal signaling-disk U. A springfinger, K, bears against the periphery of said disk and is electrically connected to l1ne F. In the periphery of said disk are inserted pieces, V, of insulating material, so that, in a manner now well known, when said disk 1s rotated by the spring-motor mechanism,electr1cal communication with it is ruptured whenever the pieces V co me under the finger. The clocktrain also actuates an escapement-wheel, a. On the under side of the armatureG is shown a stop or projection, b, adapted to engage with the escapement wheel a and preventthe same, and hence the clocktrain and disk U, from turning.

The normal condition of the parts above described is as represented in Fig. 1, the cmcuit then being as follows: from the line F to contact M, arm J, branch lines 0 E, and magnet-coils D B to point N, armature-arm Q, and continuation of line F, which is here shown connecting with the armature G at its pivotpoint. The magnet A will then be neutral, the armature Gwill be depressed, and the stop b thereon,engaging with the escapement-wheel a,will prevent any movement of the train and disk U.

Suppose, now, for example, that the branch line 0 be cut. The equilibrium of the opposing currents being destroyed, magnet A will attract armature G, the arm J on said armature will break contact with the point M, and the arm Q with the point N. The points N and M, however, are preferably made as springfingers, so as to keep contact with the armature until just before the arm Q engages and is caught by the spring-catch R, by which means the armature becomes held in its attracted position even after circuit through the magnet A-is broken. At the same time the step b is lifted from the escapement-wheel a and the disk U is rotated. The main-line current,now no longer passing to the branch lines 0 and E, passes by the finger K to disk U, and thence by the wire F, which maybe electrically connected to the arbor of said disk,to the catch B, thence to the armature-arm Q, so to the line F. Meanwhile the revolution of disk U makes and breaks the circuit between F and F in accordance with the arran gement of contact-pieces V on the periphery of said disk, and in this way, as is well known, an electric bell or any other alarm apparatus at a central station may be actuated to produce material, I, so that and a desired corresponding signal; The position of the parts duringthe foregoing operation is shown in Fig. 2. a

The above-described mechanism is one operative' means of carrying my invention into practical effect to give a beneficial result.,

Other means may be adapted to the same end, operating in substantially like manner. I therefore do not limit myself to theprecise means and instrumentalities here described.

I claim 1. The combination of a-source of electricity, a main line having two branch circuits, a differential electro-magnet having its coils interposed in said branch circuits, an armature in the field of said magnet, analarm-signaling mechanism included in main line and controlled by said armature, and a circuit-closer interposed between said two magnet-circuits and said main line, the aforesaid parts being so constructed and arranged that when the'armature is attracted by said magnet it shall open said circuit-closer,and so break connection between said magnet-circuits and main line.

2. The combination, in a fire or burglar alarm system, of a source of electricity, a main line having two branch circuits, a differential electro-magnet having its coils included in said branch. circuits, an armature forsaid electro-magnet, and, controlled by said armature andincluded in said mainline, an automatically-operatcd circuit-breaking wheel, and a circuit-closer interposed between said magnetcircuits. and said main line, the aforesaid parts being so constructed and arranged that when .the armature his attractedbysaid magnet it shall release the said circuit-wheel and open the said circuit-closer to break connection between said-magnet-circuits and main line.

spective circuits of said'branch conductors, I

an armature in the field of said magnet, and three circuit-closers controlled by said armature when actuated bysaid magnet, one of said I I circuit-closers making and breaking circuit through main line between the shunt-terminals, and the other two circuit-closers respect- ,ively making and breaking circuit at each point of connection of said shunt-terminals with mainline, substantially asdescribed.

WILLIAM A. BARNES. 

